With certain agricultural practices, the usual prior art method of applying chemicals such as fertilizer, herbicides, pesticides, fungicides, growth retardants, and related chemicals involves surface application of liquid or solid material. Surface application of material ultimately targeted for subsurface structures is inefficient because of physical forces acting on the material after it has been applied but before it has soaked or percolated to the target root structures. These physical forces include wind and air current drift, surface water induced runoff, ultraviolet breakdown of the agrochemical, and impenetrable soil surface. Surface application of material ultimately targeted for subsurface structures can have negative effects on the environment due to residue surface accumulation of chemicals and subsequent contamination of surface water due to runoff.
There are certain situations where it is possible to till the soil and to apply the agrochemical into the subsurface at the till. In many situations this is not desirable such as in no-till farming, or in maintenance of pastures, golf courses, parks, right-of-ways, and related areas. Various attempts at using a narrow chisel plow or knife to make a slit in the soil and applying the chemical in the narrow slit have proved impractical. Common problems encountered have been difficulty in keeping the chisel in the ground in hard soil, and excessive wear of the chisels.
Other attempts have been directed toward jet injection of chemicals into the soil. Among these are a proposal disclosed in U.S. Pat. No. 4,624,193. This disclosure utilized the power take-off of a tractor to power a pump where the entire pump output was directed to a single nozzle at a time. This disclosure lacked the ability for continuous injection from a plurality of nozzles. The presently disclosed invention utilizes a separate motor to power a high pressure piston pump sufficient to generate liquid jets which are continuous and from a plurality of nozzles.
Attempts at jet injection have been complicated by clogged nozzles. This problem is circumvented in the present disclosure by using an anti-fouling shield pan which rides on the surface and has orifices through which the liquid jets pass. These shield pans keep the injection nozzles close to the ground without exposure to debris.